Pulse-echo technique

Ultrasonic Testing of Concrete with Fast Imaging Pulse-Echo-Technique. 

Due to the outer circumference of the silo, about 25 meters, a non- or rarely destructive testing method was needed for the localization. Because the building was still in use, it was only accessable from the exterior side. We chose the ultrasonic pulse-echo-technique as an appropriate way of doing the testing. 

Hillger, W. Inspection of Concrete by Ultrasonic-Pulse-Echo-Technique, In Proceedings of the European Conference on Non Destructive Testing, Nice 1994, pp. II59-II63... 

The result from the work shows that we can obtain good approximations of the attenuation values using pulse echo ultrasound. This indicates that it will be possible to replace the through-transmission technique by a pulse echo technique. 

Data from ref [31] the elastic constants were measured by the pulse-echo technique j3 was determined from low-temperature specific heat data. 

Geography, Geology Pulse/echo techniques are used in the location of mineral and oil deposits and in depth gauges for seas and oceans. Echo ranging at sea has been used for many years (SONAR). 

Figure 10. Ultrasonic pulse-echo technique for determining the thickness of layers in multilayer materials.

Povey, M.J.W., Wilkinson, J.M. 1980. Application of ultrasonic pulse-echo techniques to albumen quality testing - a preliminary report. Br. Poult. Sci. 21, 489-495. 

The acoustic velocity of SiC has been measured using both ultrasonic resonance [1] and ultrasonic pulse echo techniques. The latter has resulted in the appearance of CVD-SiC diaphragms in commercially available speakers [2]. 

PULSE-ECHO TECHNIQUES - Corrosion detecting processes which, by recording the action of ultrasonic waves artificially introduced into production structures, can determine metal thickness and detect flaws. 

The two major techniques in ultrasonic testing arc the pulse-echo mode and the through-transmission mode. In pulse-echo mode, the same transducer is used to emit and receive ultrasonic waves and requires access to only one side of the structure inspected (Fig. 12). The pulse-echo technique is effective on the near side skin laminate only, and the sensitivity decreases as a function of depth [29]. With the through-transmission mode, access to both sides of a structure is required as an emitter probe is placed on one side and a receiver on the other (Fig. 13). This technique measures the signal amplitude of ultrasonic waves transmitted through the material tested and is more sensitive to small defects than the pulse-echo mode. The detection of flaws throughout the whole depth of a... 

Schw artz suggests the use of the pulse-echo technique for the inspection of glass fiber bonds and delaminations in fiberglass laminates up to 19 mm thick, the through-transmission technique to inspect sandwich constructions, and thick fiber glass laminates and the resonant frequency for detection of disbonds in glass-fiber metal bonds [87],... 

The resulting resolution of the above technique Is A/4 perpendicular to the beam axis (A = crystal size) and a qtiarter of the pulse length along the beam axis (ref 3). The equivalent conventional pulse-echo technique resolutions are RX/A (R = range of Inspection,... 

An Image of the crack tip at one position Is given In Fig. 9 (exact sizes etc cannot be given for commercial reasons). The comparison of these results with a destructive examination of the component should be available In the near future. However, once the turbine blades and shrunk on discs were removed It was possible to Inspect the Interdlsc groove area at a closer range with conventional pulse-echo techniques. The results of this Investigation have supported the SAFT results. 

Both methods use the pulse-echo technique. A pulse is sent into the sample, where it is reflected by the front and back surfaces of the material and returned at reduced amplitude to the transducer, while the waveforms are monitored on a recording oscilloscope. From the timing and amplimde of the reflected waves the sound speed and attenuation of the material may be determined. Successive reflections provide additional information on both these properties. A typical ultrasound pattern obtained using the direct-coupled transducer method is shown in Fig. 60.4. 

Figure 15.12 Ultrasonic pulse-echo technique for detection of adhesion flaws.

The glass density (d) was measured on powdered samples by the pycnometry method with an accuracy of 0.005 g cm Young s modulus ( ) and Poisson s ratio (y) were measured by the pulse-echo technique on 4 mm thick rectangular specimen. Vickers indentations (load of 9.8 N apphed during 15 s), were performed to estimate both Meyer s hardness (H) and the indentation fracture toughness (Kc) by means of the following equations ... 

Piezoelectric transducers are key components in medical ultrasound imaging and are used both as the acoustic source and the detector (pulse-echo technique). The uses for ultrasound are numerous and include examination of the fetus in the mother s womb as shown in Figure 31.22 and high-resolution imaging of intravascular structures. PZT is the ceramic of choice for this application mainly because it has a high k and is inexpensive compared to some of the other options such as polymer piezoelectrics. 

Pulse echo technique-. A technique in which the reflection of an ultrasonic pulse on material heterogeneities is analyzed in order to characterize their in-depth position and extension. Time-of-flight technique A technique where the relation between the pulse paths at various positions of examined object or wave angles of incidence are used for the description of the acoustic impedance heterogeneities. 

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